Monsters Unleashed V.1
This pdf from Purple Duck Games is 7 pages long, 1 page front cover and comes with an extra pdf for SRD and a 1-page extra containing tokens.
Eight months on and Thunderstone is still one of the most highly requested games in my house. However, when you play a game that many times its essential that you change it up as often as you can and so that brings me to another Thunderstone Expansion, Wrath of the Elements.